Mayavi mlab_source.set opacity doesn`t work

Question

I have two parts of code: This part works perfictly:

        @on_trait_change('scale_range, scene.activated')
        def update_range(self):
            label_unique = labels[0]
            self.cur_scale = self.scale_range
            cur_scallars_len_list = [np.array(x) for x in scallars_len_list[0]]
            for ii in range(len(label_unique)):
                points_dict[label_unique[ii]].mlab_source.set(
                    scalars=cur_scallars_len_list [ii]*self.cur_scale)

And this doesnt work and i get no errors:

@on_trait_change('opacity_range, scene.activated')
 def update_opacity(self):
    label_unique = labels[0]
    self.cur_opacity = self.opacity_range
    for ii in range(len(label_unique)):
        points_dict[label_unique[ii]].mlab_source.set(opacity=self.cur_opacity/100).